DE1782475A1 - Hydraulic power lift on a tractor - Google Patents

Description

KLÖcKNER-HüMBOLDT-DEÜTZAG-KÖLM 5 Cologne-Deutz, Sept. 4. 1968

D 68/58 - TP Da / B

Hydraulic power lift on a tractor

The invention relates to a hydraulic power lift for raising and lowering an implement on a tractor, with a control device which has a multi-position slide whose positions are determined by the actual values and Setpoint values of the working resistance or the position of a connected Working device as well as one connected to this multi-position slide by a control line, the inflow to the lifting cylinder the main control element dominating the power lift, its slide is pushed into the closed or open position with the aid of hydraulic actuators, the lifting cylinder in the closed position of the power lift pressure medium is supplied, while in the open position the promotion is interrupted and instead the pressure medium pump promotes in a pressureless room.

It is known to limit the pressure in the lifting cylinder of the Brift lifter to a maximum value for the constant transfer of a partial load from the implement or from an Anhäijpr to the drive axle of the tractor as an axle load reinforcement. According to US Pat. No. 2,779,604 , in order to limit the pressure in the lifting cylinder, the latter is connected to an outflow element, the closing body of which is loaded by a compression spring whose preload can be changed at will . When the maximum pressure preselected with the aid of the compression spring is exceeded in the lifting cylinder, the

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Closing body moved against the force of the compression spring, so that the pumped excess pressure medium in a unpressurized space can flow off. However, this discharge element has the disadvantage that the pressure medium pump during the load transfer must constantly promote against a relatively high pressure, which in addition to an inadmissible heating of the pressure medium severe wear occurs, in particular the control edges of the outflow element.

From DAS 1 179 033 is to switch off the pressure medium supply a power lift became known in the control device to the control line between the multi-position slide and the Main control element to connect an outflow element which has a closing body spring-loaded in the direction of flow. Taking off the closing body from its seat is carried out by a plunger, which is in each case in the upper end position of the lifting arms of the The power lift is displaced axially against the closing body by a cam arranged on the lifting shaft. In this known device is therefore a travel-dependent shutdown of the power lift

The object of the invention is that geschillert s disadvantages 5 and avoid "and a means for tJlaertragun" a partial load of a hydraulic power lift of the type mentioned: to create work unit or a trailer on the drive axle of a f tug at in each case When the preselected maximum pressure in the lifting cylinder is reached, the pressure medium pump is automatically switched to pressureless circulation.

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The object is achieved according to the invention in that upon actuation of the hydraulic power lift in the sense of lifting, depending on the pressure increasing in the lifting cylinder, via suitable hydraulic switching elements the pressure line leading from the pressure medium pump to the lifting cylinder in front of a built-in pressure line Check valve is connected to an unpressurized space. By means of these measures, each time the axle load increase is reached preselected pressure in the lifting cylinder of the power lift interrupted the supply of pressure medium to this and the corresponding Switching element diverted to a pressureless room. Thus, there are problems of excessive heating of the pressure medium and an unacceptably high level of wear and tear on the control edges of the corresponding control member does not occur.

In the case of a hydraulic power lift, on its control line Aoströmorgan with one in the closing direction by a compression spring loaded closing body is connected, it is provided according to the invention that the closing body of the outflow organ in on known way constantly against its closing direction under the action of the prevailing in the lifting cylinder of the power lift Pressure is and the bias of the compression spring of the closing body can be changed arbitrarily.

The invention can also be carried out so that the main control member a second control element is connected in parallel, which apart from hydraulic actuators also has one in the opening direction acting compression spring has that the actuator acting in the closing direction directly and the actuator acting in the opening direction both via a throttle

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the control line as well as with a discharge element in connection stands, which has a closing body loaded against its closing direction with a compression spring, which in turn is constantly in the closing direction under the action of the pressure prevailing in the lifting cylinder of the power lift and that the bias the compression spring of the closing body can be changed arbitrarily.

In this solution, for simplification, the main control unit and this control member connected in parallel to be combined into a single control member, which hydraulic actuators and additionally a compression spring acting in the opening direction aufv / eist, with the actuator acting in the closing direction directly on the control line and the one in the opening direction Acting actuator sov / ohl via a throttle to the pump pressure line as well as is connected to the outflow organ.

Furthermore, the invention can be designed so that the closing body of the outflow element is designed as a longitudinal slide at least at the end facing away from the compression spring, the free The front face is acted upon by the pressure in the lifting cylinder and in its IHihrungsbohrung an annular groove dominated by the longitudinal slide has, which is in communication with a pressureless space.

Two exemplary embodiments of the invention are shown schematically in the drawing. Show it:

Fig. 1 shows the hydraulic circuit diagram of a power lift system with a discharge element influenced by the pressure in the lifting cylinder according to the invention}

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Fig. 2 the hydraulic circuit diagram of a power lift system with a control element connected in parallel to the main control element, which is controlled by an outflow element influenced by the pressure in the lifting cylinder;

Fig. 3 Details from the circuit diagram according to Fig. 2, with the main control element and that connected in parallel Control organ are combined into one control organ.

In the linkage system shown in Fig. 1 is a D _r uckmittelpumpe is connected through a pressure line 2 to a main control element 3, the hydraulic actuators 4 and 5 and also on the left hand side of the compression spring 6 has. The pressure line 2 is connected to a multi-position slide 9 by a control line 7 into which a throttle 8 is connected. In addition, the pressure line 2 is connected by a line 10 to a check valve 11, which in turn is connected to the lifting cylinder 13 of the power lift via a line 12. A line 14 leads from the line 10 to the actuating element 5 of the main control element 3. In addition, the control line 7 is connected by a line 15 to the actuating element 4 of the main control element 3. A line 16 branches off from the line 12 and leads to the multi-position slide 9 with the activation of a throttle 17. An outflow element 18, which has a closing body 19 in a housing, is connected to the control device described. The closing body 19, which has a cylindrical part 20 and a conical part 21, is supported via a compression spring 22 against a spindle 23 which can be axially adjusted by hand. The cylindrical part 20 of the Säiließkörpers 19 sits in a

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Mihrungsbohrung 24, which in turn by a line 25 with the line 12 or with the lifting cylinder 13 of the power lifter in connection stands. Furthermore, there is 24 in the miter bore an annular groove 26 which is connected by channels 27, 28 to an unpressurized space. The conical part 21 of the closing body 19 dominated an annular space 29, the through a bore 30 and a line 31 connected to it with the control line 7 of the regulating device communicates. The pressure medium reservoir from which the pressure medium pump 1 sucks pressure medium and into the the pressure medium finally flows back is denoted by 32 been.

The operation of the device described is as follows: Assume that the multi-position slide 9 is in the one shown Neutral position, the control line 7 is pressureless, while the pressure line 2 is due to the throttle 8 and the main control element 3 located throttle has such a pressure that, with the aid of the actuating member 5, the main control slide 3 stops in the left end position shown. Will rtan through one of the SoXIf or actual value transmitter of the Control device initiates a lowering impulse, the meter * Position slider 9 moved to its right end position. Hi erdurcli the lifting cylinder 13 of the power lift is carried through the lines 12

and 16 as well as the throttle 17 with the ictickaittelvorratsbehltlter 32P connected, so that pressure medium can flow away from the lifting cylinder and thus an implement held by the power lift is lowered. If, on the other hand, the multi-position slide 9 is controlled by one of the donors is moved to the left end position, this is next to the

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line 16 also the control line 7 blocked. This builds up in the control line 7, a pressure applied via the actuating member 4, supported by the compression spring 6, the main control member moves to the right end position. The pressure now building up in the pressure line 2 and also in the line 10 has to As a result, pressure medium passes through the check valve 11 and line 12 to the lifting cylinder of the power lift. One on the hitch connected implement is thus raised. Is now provided, the device described for controlling the power lift when transferring a partial load from an implement or a trailer to the driving axle of the tractor to increase the axle load to use, the extended position slider 9 is moved to its left end position, ie to lift, with the aid of the setpoint generator set. Pressure medium is thus supplied to the lifting cylinder 13 of the power lift. The pressure in the lifting cylinder 13 in each case is through the line 25 and the bore 24 on the left end face of the cylindrical part 20 of the closing body 19 transferred. The conical part 21 of the closing body 19 is through the Force of the spring 22 is initially held in the closed position, so that the same in the annular space 29, in the bore 30 and in the line 31 The pressure conditions prevail as in the control line 7. The pressure on the left end face of the cylindrical part 20 now predominates the force of the spring 22, the closing body 19 is displaced to the right against the spring and consequently the entry space 29 becomes through the space of the spring 22 and the channel 28 with the pressure medium supply sbehält it 32 connected. This breaks the pressure in the annular space 29, in the bore 30 as well as in the line 31 and in the control line together, so that the main control member 3 is shown in its left

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End position is shifted. The pressure medium conveyed by the pump 1 now flows back through the pressure line 2 and the main control element to the pressure medium reservoir 32 and. it. ^ e Iv igt Iveia Druo>.; - medium more to the lifting cylinder 13 of the power lift. If the partial load transferred from the implement or the trailer to the drive axle of the tractor is too large or too small, a correspondingly smaller or larger preload of the compression spring 22 can be selected by turning the spindle 23. Pur the Pail that the pressure in the lifting cylinder 13 rises above the set target value, the closing body 19 is moved so far to the right until finally a pressure relief through the annular groove 26 and the channels 27, 28 takes place. Of course, when the control device is used to control a working device, the compression spring 22 must be so strongly preloaded according to the working resistance or the position that the control processes initiated by the actual value transmitter are not impaired.

The control device of a hydraulic power lift shown in Fig. 2 is correct in its structure and mode of operation essentially coincides with that in Fig. 1. The same reference numbers have therefore been used for the same parts. At the control device According to FIG. 2, a line 34 branches off from the pressure line 2 and is connected to a control element 35. The control member 35 has a hydraulic actuator on each side 36 or 37 and is also loaded on the right side by a compression spring 38. From the actuator 36 leads a line 39 to the control line 7, while a line 40 leads from the actuating member 37 to a discharge valve 41. The two lines 39

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and 40 stand through a line 42 into which a throttle 43 is switched on is related to each other. The drain valve 41 has a housing 44 with a guide bore 45 in which a Longitudinal slide trained closing body 46 is arranged. The guide bore 45 is on the left side of the closing body connected by a line 47 to the line 12 or to the lifting cylinder 13 of the power lift. Supports on the right side the closing body 46 abuts against a manually axially adjustable spindle 49 via a compression spring 48. With the help of the spindle 49. the bias of the compression spring 48 can be continuously changed / grounded. In the closing body 46 there is an annular groove 50 which on the one hand through a channel 51 with the line 40 and on the other hand through a channel 52 to the pressure medium reservoir 32 connected. The guide bore 45 has a hooking groove 53 in the area of the closing body 46, which in turn passes through a channel 54 communicating with the channel 52.

The operation of the device described in Fig. 2 is as follows:

The mode of operation of the control device for controlling an implement according to the working resistance or according to the position is already explained in the description of Fig. 1. Should now the control device in connection with the discharge valve 41 for controlling the power lift when transferring a partial load from one Implement or a trailer on the drive axle of the tractor are used to increase the axle load, the Multi-position slide 9 with the help of the setpoint device in its left end position, ie set to lifting. This results in

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a pressure build-up in the control line 7, although from here a small amount of pressure medium can constantly flow out to the pressure medium reservoir 32 through the line 39, throttle 43, lines 42, 40 and the drain valve. However, the pressure build-up in the control line is sufficient to move the main control element 3 from the position shown into the closed position. At the same time, the control member 35 is also pushed into the closed position with the aid of the actuating member 36. Since the pressure line 2 is now blocked with respect to the pressure medium reservoir 32, the pump 1 conveys pressure medium through the line 10, the check valve 11 and line 2 to the lifting cylinder 13 of the power lift. The pressure in the lifting cylinder 13 constantly acts on the left end face of the closing body 47. If the pressure on the left end face of the closing body 46 now outweighs the force of the compression spring 48, the closing body 46 is displaced to the right against the force of the compression spring and thereby blocks the line 40 from the pressure medium reservoir 32. Pressure builds up in the throttle 43 downstream lines and thus also in the hydraulic actuator 37, which finally, supported by the force of the compression spring 38, moves the control member 35 into a left end position. That from the pump 1 ge: F8rl «Tte DruoiKLt * ®! now flows through the pressure line 2 into the line 34 ^{and from} here through the control member 35 to the pressure medium storage container 32 and no more pressure medium reaches the lifting cylinder 13 of the power lift. By changing the bias of the compression spring 48, the pressure in the lifting cylinder 13 and thus the partial load to be transmitted from the implement or from the trailer to the drive axle of the tractor can be determined. Should the pressure

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in the lifting cylinder 13 of the power lift over the set target value rise outwards, the closing body 46 is pushed to the right until there is finally a pressure relief through the annular groove 53 and the channels 54, 52 takes place.

In Fig. 3 it is shown how, instead of the two control members 35 and 35 according to Fig. 2, you can manage with only one control member 56, without thereby significantly changing the effect of the facility. The control member 56 has a hydraulic actuator 57 or 58 on each side and is also on the right side a compression spring 59 is loaded. A line 60 leads from the pressure line 2 to the control member 56. The actuating member 57 of the control member 56 is connected to the Steierleitung 7 by a line 61, while the actuator 58 is in communication with the line 10 by a line 62. From line 62, in the one throttle 63 is switched on, a line 64 branches off between this and the actuating member 5ö, which leads to the discharge valve 41 leads.

The mode of operation of the control member 56 is as follows: In the neutral position of the multi-position slide (not shown in FIG. 3) 9, the control member 56 has the left end position shown. If the multi-position slide 9 is now adjusted to lift to the To achieve the aforementioned axle load gain with the aid of the power lift, a pressure builds up in the control line 7, which Moves the control member into its right end position via the line 61 and the actuator 57. This becomes the lead locked and it "builds up in the pressure line 2 and in line OK

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One press and it becomes the lifting cylinder 13 of the power lift Pressure medium supplied through the check valve 11. The pressure build-up in line 2 or in line 10 only has an effect insignificantly on the actuator 58, since through the line 64 and the discharge valve 41 pressure medium can flow off. The actuator 58 thus initially changes the position of the control member 56 not. Finally, the discharge valve 41 is closed by the pressure in the lifting cylinder 13 of the power lift and thus the Line 64 to the pressure medium reservoir 32 blocked, then A pressure builds up in this line and in the actuating member 58, which brings the control member 56 back into the open position shown shifts. This interrupts the supply of pressure medium to the lifting cylinder of the power lifter and that which is funded by the pump Pressure medium flows through the pressure line 2 and the line 60 and the control member 56 directly to the pressure medium reservoir 32 back.

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Claims (5)

5 Cologne-Deutz, Sept. 4, 1968 claims 1. ) Hydraulic power lift for lifting and lowering an implement on a tractor, with a control device which has a multi-position slide, the positions of which are determined by the actual values and setpoints of the working resistance or the position of a connected implement, as well as a control line connected to this multi-position slide , the inflow to the lifting cylinder of the power lift dominating the main control element, whose slide with the help of hydraulic actuators in locking or The opening is pushed, whereby in the closed position pressure medium is fed to the lifting cylinder of the power lift, while in the open position the conveyance is interrupted, and instead the pressure medium pump conveys into a pressureless space, characterized in that when the hydraulic power transmitter is actuated in the sense of lifting, depending on the pressure increasing in the lifting cylinder (13), via suitable hydraulic switching elements (18, 35, 41 56) the pressure line (10) leading from the pressure medium pump (1) to the lifting cylinder (13) upstream of it built-in check valve (11) is connected to an unpressurized space (32). 1098 35/0652 4.9.68 D 68/58 2. Hydraulic power lift according to claim 1, wherein to the control line an outflow element with a through in the closing direction a compression spring loaded closing body is connected, characterized in that the shooting body (19) of the outflow element (18) in a manner known per se, constantly against its closing direction is under the action of the pressure prevailing in the lifting cylinder (13) of the power lift and the bias of the compression spring (22) of the closing body (19) can be changed arbitrarily. 3. Hydraulic power lift according to claim 1, characterized in that that the main control element (3) a second control element (35) is connected in parallel, which apart from hydraulic actuators (36, 37) additionally has a compression spring (38) acting in the opening direction so that it is in the closing direction acting actuating member (36) directly and the actuating member (37) acting in the opening direction both via a throttle (43) with the control line (7) as well as with a discharge element (41) is in connection, which has a closing body (47) loaded against its closing direction with a compression spring (48), which in turn is constantly in the closing direction under the action of the pressure prevailing in the lifting cylinder (13) of the power lift stands and that the bias of the compression spring (48) of the closing body (46) can be changed arbitrarily. 109 83 5/0652 4.9.68 D 68/58 4. Hydraulic power lift according to claim 3, characterized in that that the main control element (3) and the control element (35) connected in parallel to form a single control element (56) are summarized, which hydraulic actuators (57, 56) and additionally a compression spring acting in the opening direction (59) and that the actuating member (57) acting in the closing direction is directly connected to the control line (7) and that in the opening direction Acting actuator (58) both via a throttle (63) to the Pampenaruckleitung (2) and to the outflow element (41) is connected. 5. Power lift according to claims 1 to 4, characterized in that the closing body (19, 46) of the outflow element (18 or 41) at least at the end facing away from the compression spring (22 or 48) is designed as a longitudinal slide whose free end face is acted upon by the pressure in the lifting cylinder (13) and which in its guide bore (24 or 45) has an annular groove (26 or 53) dominated by the longitudinal slide, which is connected to a pressureless bar (32). 109835/0652